We have proposed studies of the molecular biology of animal cell surfaces. We are interested in the ability of surface components to regulate cell growth and to participate in lymphocyte mediated tumor regression. Spontaneously and virally (Py,SV40, and MSV) transformed cell lines have been derived from primary and established lines of Balb/c mice (3T3 cells). We are studying ability of these cells to catalyze complex polysaccharide biosynthesis using whole cells incubated in the presence of nucleotide sugars. And, structural and compositional studies of glycoprotein and glycolipids have been undertaken. We are using these cell lines to induce tumors in Balb/c mice. The ability to distinguish between transformed and normal cell lines in lymphocyte mediated cytotoxicity will be determined using lymphoctyes from tumor bearers. We want to determine if antigens prepared from cell surfaces can act as a blocking factor in lymphocyte mediated cytotoxicity. We hope to be able to use the blocking ability of antigens to assay for cell surface components functioning in tumor regression. By characterizing these components, we hope to draw inferences both on cell surface changes accompanying transformation, and on the molecular basis of tumor rejection.